| 
           Operating and Reporting Segments (Details) (USD $) 
        In Thousands, unless otherwise specified  | 
        3 Months Ended | 9 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 
           Sep. 30, 2014 
         | 
        
           Sep. 30, 2013 
         | 
        
           Sep. 30, 2014 
         | 
        
           Sep. 30, 2013 
         | 
      |||||||||
| Revenue | ||||||||||||
| Revenue | $ 556,776 | [1] | $ 492,080 | [1] | $ 1,470,725 | [1] | $ 1,278,465 | [1] | ||||
| Segment operating income | ||||||||||||
| Segment operating income | 50,822 | 63,965 | 152,449 | 137,667 | ||||||||
| Financial Services Profit | 4,294 | 4,294 | 10,936 | 11,515 | ||||||||
| Corporate and unallocated | (9,490) | [2] | (8,662) | [2] | (22,823) | [2] | (22,011) | [2] | ||||
| (Loss)/earnings from other unconsolidated entities, net | (134) | 46 | (364) | (229) | ||||||||
| Interest expense | (460) | (3,462) | (4,569) | (13,113) | ||||||||
| Other income, net | 1,998 | 605 | 6,395 | 1,760 | ||||||||
| Loss on early extinguishment of debt | 0 | 0 | 0 | (3,796) | ||||||||
| Earnings before income taxes | 47,030 | 56,786 | 142,024 | 111,793 | ||||||||
| 
           West [Member] 
         | 
        ||||||||||||
| Revenue | ||||||||||||
| Revenue | 234,950 | 259,669 | 659,596 | 695,615 | ||||||||
| Segment operating income | ||||||||||||
| Segment operating income | 22,204 | 41,298 | 74,398 | 95,356 | ||||||||
| 
           Central [Member] 
         | 
        ||||||||||||
| Revenue | ||||||||||||
| Revenue | 179,761 | 139,307 | 459,619 | 357,406 | ||||||||
| Segment operating income | ||||||||||||
| Segment operating income | 19,323 | 12,677 | 47,512 | 22,320 | ||||||||
| 
           East [Member] 
         | 
        ||||||||||||
| Revenue | ||||||||||||
| Revenue | 142,065 | 93,104 | 351,510 | 225,444 | ||||||||
| Segment operating income | ||||||||||||
| Segment operating income | $ 9,295 | $ 9,990 | $ 30,539 | $ 19,991 | ||||||||
          
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